This invention relates to a sealing apparatus, and more particularly to a sealing apparatus suitably used in a hub unit, a water pump or a motor which serves as a rolling bearing, and a bearing apparatus having the same.
One conventional sealing apparatus is described in JP-UM-A-64-55371.
This sealing apparatus includes a slinger, a core metal portion, and an elastic member.
The slinger has a generally cup-shape in an axial cross-section.
In the above cross-section, the core metal portion bisecting the slinger generally perpendicularly, and extends in a radial direction.
The elastic member includes a base portion, and four thrust lips. The base portion has a generally block-shape, and is fixed to the core metal portion in a manner to cover the periphery of the core metal portion. First two of the four thrust lips are spaced from each other in the radial direction, and extend axially from a portion (which is not a distal end) of the base portion disposed at one axial side of the core metal portion, and contact the slinger generally in the axial direction. The other two of the four thrust lips are spaced from each other in the radial direction, and extend axially from a portion (which is not a distal end) of the base portion disposed at the other axial side of the core metal portion, and contact the slinger generally in the axial direction. An axially-outward portion of a distal end portion of the slinger of the generally cup-shaped cross-section where an opening is provided is bent inwardly perpendicularly relative to the axial direction, and contacts the base portion generally in the axial direction.
In the above conventional sealing apparatus, the slinger and the elastic member are contacted with each other at the five regions in the axial direction, and by doing so, a pressing force applied from the elastic member to the slinger is markedly increased so that even when the positional relation between dust strips and the slinger is varied by a change in axial force of a rotation shaft, a sealing ability will not be lowered.
In the above conventional sealing apparatus, however, the pressing force applied from the elastic member to the slinger is markedly increased, so that a torque is increased, which leads to a problem that fuel consumption of an automobile or the like provided with this sealing apparatus is increased.
Furthermore, the effect of discharging muddy water, passed through the area between the elastic member and the slinger, to the exterior is small, and this invites a problem that there is a possibility that the muddy water passing through first two or three of the five contact regions between the elastic member and the slinger intrudes into the interior through the sealing apparatus.